Most vehicles are provided with a heating apparatus to maintain a comfortable internal environment wherein internal air is heated using engine cooling water at high temperature. The cooling water heated by the engine is transferred to a heater core through a cooling water pump. Then, external air or internal air is heated by a blower and delivered into the vehicle.
There have been proposed many heating apparatuses for a vehicle which employ the above-mentioned heating principle with additional functions to improve the efficiency of the heating. For example, Japanese Patent Publication No. 2003-104041 discloses a fluid heating apparatus to improve the heating capability and capacity of a vehicle by installing an additional fluid heating apparatus at the inlet of a heater core. Further, Japanese Patent Publication No. 2002-283826 discloses an air conditioning apparatus for a vehicle which independently controls the temperature in front and rear seats using a bypass and an air mix door. Further, Japanese Patent Publication No. 2002-283826 discloses an air conditioning apparatus for a vehicle to obtain sufficient conditioning effect at the bi-level mode. Also, Japanese Patent Publication No. 6-328930 discloses a heating apparatus for a vehicle in which the inside of the vehicle and an engine can be promptly heated by supplying high temperature cooling water saved in a thermo vessel to the inside of the vehicle or the engine.
As is shown in the prior art, heaters are basically designed to provide warm or hot air. Therefore, when an engine is under operation, cooling water automatically flows into a heater core through conduits. However, this still holds true even during the summer when it is hot or the interior temperature of the vehicle is above the preset standard temperature. Consequently, if fresh high temperature cooling water flows into the heater core and is circulated, heat is continuously irradiated toward the outside of the heater core case, thereby continuously increasing the interior temperature. Further, considering that air conditioning is controlled by way of on-off of an air conditioner switch, the interior temperature of a vehicle will be increased according to the increase in interior of the vehicle if the air conditioner is not in a proper working condition or if is on an off position.
Therefore, when the interior of a vehicle is below a preset standard temperature with the temperature controlling lever placed at a cooling side, all cooling water passes through the heater core thus resulting in decrease in cooling efficiency. Therefore, there has been a need for the development of a new method to solve the above-mentioned problems.